<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button id="mybutton"></button>
</body>
<script>
    function foo(){
        var el = document.getElementById('mybutton')
        el.onclick = function(){
            console.log(el.id);
        }
        el = null;
    }
    foo();
    var tmp = 123;
    if (true) {
        let tmp;
        tmp = 12;
    }
    var arr = [12,34,32,89,4];
    console.log(Math.min(...arr));
    function inner(){
        let myLet = 12;
        return function inner2(){
            let myLet = 13;
            console.log(myLet);
        }
    }
    inner()();
    var a = 10;
    var obj = {
        a:20,
        fn(){
            setTimeout(function(){
                console.log('---',this.a);
            })
        }
    }
    obj.fn();
</script>
</html>